JP3677953B2 - Fuel supply control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel supply control device for an internal combustion engine, and more particularly to a technique for smoothly switching a combustion state from stratified combustion to homogeneous combustion during deceleration.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a fuel supply control device that performs fuel cut control that stops fuel supply during deceleration and suppresses HC and improves fuel consumption is known (see Japanese Patent Laid-Open No. 54-148929).
[0003]
[Problems to be solved by the invention]
Since this fuel supply control device is based on the assumption of homogeneous combustion in which a combustible mixture is burned in the vicinity of the stoichiometric ratio, there is almost no change in the target equivalence ratio during deceleration, and torque fluctuation during recovery after fuel cut is small. It didn't matter.
However, in recent years, in-cylinder injection internal combustion engines that have been developed for the purpose of improving exhaust properties and fuel consumption and injecting fuel directly into the cylinder and igniting with a spark plug, the target equivalent ratio is extremely small. Switching between stratified combustion for performing combustion and homogeneous combustion with a relatively large target equivalence ratio is performed in accordance with the engine operating state. Therefore, if the speed is reduced in a state where stratified combustion is being performed, it is necessary to switch the target equivalence ratio in accordance with switching from stratified combustion to homogeneous combustion. In this case, if the conventional fuel supply control device is applied as it is, the following problems may occur.
[0004]
(1) If the target equivalence ratio is switched at the same time as switching from stratified combustion to homogeneous combustion, the air amount at the time of switching becomes excessive, so the torque may increase rapidly and the feeling of deceleration may be impaired.
(2) In an internal combustion engine equipped with a device such as an exhaust gas recirculation device that recirculates part of the exhaust gas by introducing it into the intake system, when switching from stratified combustion to homogeneous combustion, immediately after switching due to the influence of device response delay, etc. There is a risk that the combustion of this will become unstable.
[0005]
(3) When the target equivalence ratio is changed during switching from stratified combustion to homogeneous combustion, the intermediate equivalence ratio between stratified combustion and homogeneous combustion passes, so when the fuel cut is not performed, the exhaust properties May decrease.
Therefore, in view of the above-described conventional problems, the present invention facilitates switching of the combustion state from stratified combustion to homogeneous combustion at the time of deceleration so that torque fluctuation at the time of switching, combustion instability, and exhaust It is an object of the present invention to provide a fuel supply control device for an internal combustion engine that prevents deterioration in properties.
[0006]
[Means for Solving the Problems]
Therefore, as shown in FIG. 1, the invention according to claim 1 is an internal combustion engine capable of switching the combustion state between stratified combustion and homogeneous combustion by switching the combustible air-fuel mixture in the combustion chamber between the stratified state and the homogeneous state. When the engine is decelerated during stratified combustion, the fuel supply is stopped after the elapse of a first predetermined time from the start of decelerating, and the first predetermined time elapses after the deceleration is started In the fuel supply control device for an internal combustion engine that switches from the target equivalent ratio in stratified combustion to the target equivalent ratio in homogeneous combustion until the engine is operated, the fuel supply control device for the internal combustion engine includes an operating state detecting means A for detecting the engine operating state; , detected a target equivalent ratio calculation means B for calculating a target equivalent ratio according to the operating state, computed gradually slowing as the correction to the target equivalent ratio correction changes in the target equivalent ratio to the target equivalent ratio When the switching condition determining means D for determining whether or not the switching condition from the stratified combustion to the homogeneous combustion is satisfied based on the stage C and the corrected target equivalent ratio, and the switching condition to the homogeneous combustion are satisfied, And combustion state switching means E for switching the combustion state from stratified combustion to homogeneous combustion.
[0007]
According to this configuration, the target equivalent ratio is set according to the operating state by the target equivalent ratio calculating means, and then corrected by the target equivalent ratio correcting means so as to delay the change of the target equivalent ratio. When the switching condition determining means determines that the switching condition from stratified combustion to homogeneous combustion is established based on the corrected target equivalence ratio, the combustion state switching means switches from stratified combustion to homogeneous combustion.
[0008]
Therefore, when the combustion state is switched from stratified combustion to homogeneous combustion, the target equivalence ratio gradually changes, so that the air amount does not become excessive immediately after switching to homogeneous combustion, and the torque suddenly increases. The rise is prevented.
According to a second aspect of the present invention, the target equivalent ratio calculation means is configured to calculate a target equivalent ratio to be calculated when a second predetermined time shorter than the first predetermined time has elapsed since the start of deceleration. The control is performed to switch from the target equivalent ratio in Fig. 1 to the target equivalent ratio in homogeneous combustion.
[0009]
According to such a configuration, the target equivalent ratio to be calculated is switched to the target equivalent ratio in the homogeneous combustion when the second predetermined time has elapsed since the start of deceleration. Even if a device such as a device is provided, the response delay of the device at the time of switching is absorbed.
According to a third aspect of the present invention, the switching condition determining means includes condition establishment prohibiting means for prohibiting establishment of the switching condition from stratified combustion to homogeneous combustion until the first predetermined time has elapsed. .
[0010]
According to such a configuration, since the establishment of the switching condition to the homogeneous combustion is prohibited until the first predetermined time elapses after the deceleration is started, that is, the switching to the homogeneous combustion is prohibited. Combustion is prevented from being performed at an intermediate equivalent ratio to combustion.
According to a fourth aspect of the present invention, when the target equivalence ratio corrected by the target equivalence ratio correcting means is equal to or greater than a predetermined equivalence ratio threshold value, the switching condition determining means is configured to switch from stratified combustion to homogeneous combustion. It was determined that the switching condition was satisfied.
[0011]
According to such a configuration, when the corrected target equivalence ratio is equal to or greater than the predetermined equivalence ratio threshold value, the switching condition to the homogeneous combustion is established, that is, the switching to the homogeneous combustion is performed. The determination process is very simple.
According to a fifth aspect of the present invention, the condition establishment prohibiting means limits the target equivalent ratio corrected by the target equivalent ratio correcting means within the first predetermined time to be less than the equivalent ratio threshold value. Constructed including.
[0012]
According to this configuration, the corrected target equivalence ratio is limited to be less than the equivalence ratio threshold value within the first predetermined time period. Therefore, the target equivalence ratio becomes small during the first predetermined time period, and the homogeneous combustion is reduced. Since the switching is not performed, the exhaust property is improved and the torque fluctuation when the fuel supply is stopped is suppressed.
The invention according to claim 6 is an internal combustion engine capable of switching the combustion state between the stratified combustion and the homogeneous combustion by switching the combustible air-fuel mixture in the combustion chamber between the stratified combustion and the homogeneous combustion, and decelerated during the stratified combustion. In a fuel supply control device for an internal combustion engine, the fuel supply is stopped after a predetermined time has elapsed from the start of deceleration and the target equivalence ratio is shifted to switch the combustion state from stratified combustion to homogeneous combustion. When the engine fuel supply control device switches the combustion state from stratified combustion to homogeneous combustion, the target equivalent ratio calculated according to the engine operating state is gradually changed.
[0013]
According to such a configuration, when the combustion state is switched from stratified combustion to homogeneous combustion, the target equivalent ratio calculated according to the engine operating state gradually changes, so that the air amount is excessive immediately after switching to homogeneous combustion. Therefore, a rapid increase in torque is prevented.
[0014]
【The invention's effect】
As described above, according to the invention described in claim 1 or 6, when the combustion state is switched from stratified combustion to homogeneous combustion, a sudden increase in torque is prevented, so that a decrease in the feeling of deceleration is suppressed. be able to.
According to the second aspect of the present invention, the response delay of the device is absorbed when the combustion state is switched from the stratified combustion to the homogeneous combustion, so that the combustion immediately after the switching can be stabilized.
[0015]
According to the third aspect of the invention, when the combustion state is switched from stratified combustion to homogeneous combustion, combustion is prevented from being performed at an equivalent ratio intermediate between stratified combustion and homogeneous combustion, so the fuel supply is stopped. It is possible to improve the exhaust properties in a state where the operation is not performed.
According to the fourth aspect of the present invention, since the switching determination process from the stratified combustion to the homogeneous combustion is performed very simply, the burden on the on-vehicle control device can be reduced.
[0016]
According to the fifth aspect of the present invention, since the switching to the homogeneous combustion is not performed until the first predetermined time elapses, the exhaust property is improved and the torque fluctuation when the fuel supply is stopped is suppressed. Therefore, riding comfort can be improved.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 2 shows an embodiment in which the fuel supply control device according to the present invention is applied to a direct injection internal combustion engine.
First, the configuration of a cylinder injection internal combustion engine (hereinafter referred to as “engine”) 10 will be described. A combustion chamber 13 having a predetermined volume is formed between the top surface of the piston 11 (hereinafter referred to as “piston top surface”) 11 a and the lower surface of the cylinder head 12. An intake port 15 that is opened and closed by an intake valve 14 and an exhaust valve are provided on the wall surface of the cylinder head 12 positioned above the combustion chamber 13, that is, the wall surface of the cylinder head combustion chamber 13 a formed at the lower part of the cylinder head 12. Two exhaust ports 17 opened and closed by 16 are formed in parallel.
[0018]
A fuel injection valve 18 that directly injects fuel into the combustion chamber 13 with the injection port facing the combustion chamber 13 is disposed between the intake ports 15 of the cylinder head 12. An ignition plug 19 for spark ignition of a combustible mixture of fuel and air is disposed at a substantially central portion of the wall surface of the cylinder head combustion chamber 13a.
On the piston top surface 11a, a cavity 20 having an opening formed on the upper surface is formed at a position below the line connecting the fuel injection valve 18 and the spark plug 19.
[0019]
Air is sucked into the combustion chamber 13 of the engine 10 through an air cleaner 21, an intake duct 22, an intake collector 23, an intake port 15 and an intake valve 14. The intake duct 22 is provided with an electronically controlled throttle valve (hereinafter referred to as “electric throttle valve”) 24 that changes the opening area of the passage in the intake duct 22 and is controlled based on the engine operating state. The intake air flow rate Q to the engine is controlled via 25.
[0020]
In the low load and medium load regions, fuel spray is injected into the cavity 20 at the later stage of the compression stroke, and a flammable mixture is formed in a layered manner at the lower portion of the spark plug 19 to perform stratified combustion. During the stroke, fuel spray is injected into the combustion chamber 13 to form a substantially homogeneous combustible air-fuel mixture in the combustion chamber 13 and homogeneous combustion is performed.
The engine 10 is also provided with an evaporative fuel processing device 30 for processing evaporative fuel generated in the fuel supply system. That is, the evaporated fuel accumulated in the space above the fuel tank 31 is guided to the canister 33 through the evaporated fuel passage 32 while the engine 10 is stopped, and temporarily adsorbed by the adsorbent 33a such as activated carbon in the canister 33. Is done. The upper space of the canister 33 communicates with the intake collector 23 via the purge passage 34. An electronically controlled purge valve 35 that opens and closes the purge passage 34 is interposed in the purge passage 34.
[0021]
Further, the engine 10 is provided with an exhaust gas recirculation device 40 that introduces a part of the exhaust gas into the intake system and recirculates the exhaust gas. That is, a part of the exhaust gas is recirculated to the intake collector 23 via the EGR passage 41 connected to the exhaust port 17 of the engine 10. The EGR passage 41 is provided with an electronically controlled EGR control valve 42 that controls the amount of exhaust gas recirculated in accordance with the engine operating state. Then, by opening and closing the EGR control valve 42 according to the engine operating state, exhaust gas is introduced into the intake collector 23 using the intake negative pressure, and is sucked into the combustion chamber 13 together with the intake air.
[0022]
Here, a control system of the engine 10 having such a configuration will be described.
A control unit 50 with a built-in microcomputer includes a potentiometer-type accelerator sensor 51 for detecting an accelerator pedal operation amount (hereinafter referred to as “accelerator operation amount”) APS, a crank angle sensor 52 for detecting an engine rotational speed Ne, and an engine temperature. A representative water temperature sensor 53 for detecting the cooling water temperature Tw, an air flow meter 54 for detecting the intake air flow rate Q, a potentiometer type throttle valve opening sensor 55 for detecting the throttle valve opening θ of the electric throttle valve 24, and in exhaust A signal from the O ₂ sensor 56 and the like for detecting the oxygen concentration is input.
[0023]
Various sensors such as the accelerator sensor 51 correspond to the operating state detecting means, and the control unit 50 is a target equivalent ratio calculating means, target equivalent ratio correcting means, switching condition determining means, combustion state switching means, establishment condition prohibiting means, and restriction. It has a function as a means.
The control unit 50 controls the opening degree θ of the electric throttle valve 24 according to the operation state detected based on various input signals, sets the ignition timing, and combusts at the set ignition timing. Controls to ignite the air-fuel mixture.
[0024]
Next, an outline of the operation of the present embodiment will be described with reference to the timing chart of FIG. This timing chart shows how the target equivalence ratio and the combustion state are switched when switching from stratified combustion to homogeneous combustion when deceleration is performed during the stratified combustion operation.
First, when the driver releases the accelerator pedal, the accelerator operation amount becomes equal to or less than a predetermined value, and deceleration is started. That is, it is determined that deceleration has started when the accelerator operation amount becomes equal to or less than a predetermined value.
[0025]
When deceleration is started, the basic target equivalence ratio map is not immediately switched from stratified combustion to homogeneous combustion, but the basic target equivalence ratio map is not changed immediately after starting the switching control but after a predetermined time DLTFM (second predetermined time) has elapsed. Switch the equivalence ratio map. The predetermined time DLTFM may be a constant, or may be set based on the engine operating state such as the engine speed Ne and the target torque tTc. As described above, when the basic equivalence ratio map is switched from stratified combustion to homogeneous combustion when a predetermined time DLTFM has elapsed since the start of deceleration, the evaporative fuel processing device 30 and the exhaust gas recirculation device 40, etc. The device response delay can be absorbed, and the homogeneous combustion immediately after switching can be prevented from becoming unstable due to the device response delay.
[0026]
Next, the basic target equivalent ratio TFBYA00 is set with reference to the basic target equivalent ratio map based on the engine speed Ne and the target torque tTc. The basic target equivalence ratio map referred to here refers to stratified combustion until a predetermined time DLTFM elapses after the start of deceleration, and refers to homogeneous combustion after the predetermined time DLTFM elapses.
[0027]
Then, phase lag correction is performed on the basic target equivalent ratio TFBYA00, and a corrected target equivalent ratio TFBYA4 is set. The reason for performing the phase lag correction is that when the basic target equivalent ratio TFBYA00 changes due to a change in the engine operating state, the throttle valve is controlled so that the target intake air flow rate matches the change in the basic target equivalent ratio TFBYA00. The change in the intake air flow rate is delayed due to the delay in the operation of the throttle valve and the volume of the intake system, whereas the fuel injection amount has almost no delay and can follow the change in the basic target equivalent ratio TFBYA00. This is because a delay occurs with respect to the change in the basic target equivalent ratio. Therefore, by performing the phase delay correction, the torque fluctuation at the time of switching from stratified combustion to homogeneous combustion can be smoothed.
[0028]
The final target equivalent ratio TFBYA0 is limited to the predetermined equivalent ratio TFBYADF within a cut-in delay time CFD (first predetermined time) in which fuel cut is actually started after deceleration is started. That is, within the cut-in delay time CFD, the corrected target equivalent ratio TFBY4 is compared with the predetermined equivalent ratio TFBYADF, and the smaller one is set as the target equivalent ratio TFBYA0. When the target equivalent ratio TFBYA0 becomes equal to or greater than the equivalent ratio threshold value TFACH for determining whether to switch from stratified combustion to homogeneous combustion, the combustion flag FSTRR1 is switched to homogeneous combustion. By doing so, switching of the combustion state from stratified combustion to homogeneous combustion is prohibited within the cut-in delay time CFD, so that it is possible to prevent a decrease in exhaust properties until the fuel cut is performed. .
[0029]
4 and 5 are flowcharts showing the actual switching control contents of the target equivalence ratio and the combustion state described above.
In step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), it is determined whether the engine 10 is decelerating based on the accelerator operation amount APS detected by the accelerator sensor 51. Specifically, when the detected accelerator operation amount APS is equal to or less than a predetermined value, it is determined that the engine 10 is decelerating, and if it is decelerating (Yes), the process proceeds to step 2 and must be decelerating. (No) Proceed to step 3.
[0030]
In step 2, fuel cut control during deceleration is performed. That is, as shown in FIG. 3, the fuel cut control is performed by gradually decreasing the basic injection pulse width immediately after the start of deceleration, and performing the control to make the basic injection pulse width 0 after the cut-in delay time CFD elapses. Done. The fuel cut control in this step is generally performed by an electronically controlled fuel injection device, and the control content is publicly known.
[0031]
In step 3, fuel supply control is performed when the vehicle is not decelerating. That is, the basic fuel supply amount Tp is set based on the engine rotational speed Ne, the intake air flow rate Q, etc., various corrections are performed in consideration of the cooling water temperature Tw, etc., and the effective fuel supply amount Te is calculated to obtain the effective fuel supply amount. Fuel injection is performed with a basic injection pulse width corresponding to Te. Then, this routine ends.
[0032]
In step 4, "0" is set to the homogeneous combustion switching flag FSTR0. The homogeneous combustion switching flag FSTR0 is set to “0” when switching to homogeneous combustion and “1” when maintaining stratified combustion.
In step 5, it is determined whether or not a predetermined time DLTFM has elapsed since the start of deceleration, that is, whether or not a predetermined time DLTFM has elapsed since the homogeneous combustion switching flag FSTR0 changed from “1” to “0”. When the predetermined time DLTFM has elapsed (Yes), the routine proceeds to step 6, and when the predetermined time DLTFM has not elapsed (No), the routine proceeds to step 7.
[0033]
In step 6, the equivalence ratio map reference flag FSTR1 is set to "0". The equivalent ratio map reference flag FSTR1 is set to “0” when referring to the homogeneous combustion map, and to “1” when referring to the stratified combustion map.
In step 7, a map (homogeneous combustion map or stratified combustion map) corresponding to the equivalent ratio map reference flag FSTR1 is selected, and a basic target equivalent ratio TFBYA00 based on the engine speed Ne and the target torque tTc is calculated. Here, the target torque tTc is set based on, for example, the accelerator operation amount APS and the engine rotational speed Ne. Note that the processing in step 6 corresponds to a target equivalent ratio calculation means.
[0034]
In step 8, correction control of the intake air flow rate Q is performed. That is, as shown in FIG. 3, by taking into account the response delay of the throttle valve, the throttle opening is controlled stepwise so that the actual throttle opening changes as indicated by the dotted line in the figure. To do.
In step 9, a phase lag correction process is performed on the basic target equivalent ratio TFBYA00. Specifically, when the corrected target equivalent ratio after the correction process is TFBYA4, the correction is performed by the following equation.
[0035]
TFBYA4 = FLOAD × TFBYA00
+ (1-FLOAD) × TFBYA4 (n−1)
Here, FLOAD is a weighted average coefficient set according to the engine operating state, and TFBYA4 (n−1) is the previous corrected target equivalent ratio. Note that the processing in step 9 corresponds to a target equivalence ratio correcting means.
[0036]
In step 10, based on the combustion determination flag FSTRR, it is determined whether or not stratified combustion is currently being performed. When the stratified combustion operation is being performed (Yes), the routine proceeds to step 11, and when the homogeneous combustion operation is being performed (No) this routine. End. The combustion determination flag FSTRR is set to “0” during homogeneous combustion and “1” during stratified combustion.
[0037]
In step 11, it is determined whether or not a predetermined time CFD has elapsed since the start of deceleration, that is, whether or not a predetermined time CFD has elapsed since the homogeneous combustion switching flag FSTR0 changed from “1” to “0”. When the predetermined time CFD has elapsed (Yes), the routine proceeds to step 12, and when the predetermined time CFD has not elapsed (No), the routine proceeds to step 13.
[0038]
In step 12, the corrected target equivalent ratio TFBYA4 is set as the target equivalent ratio TFBYA0.
In step 13, it is determined whether or not the corrected target equivalent ratio TFBYA4 is equal to or greater than a predetermined equivalent ratio TFBYADF. move on.
[0039]
In step 14, a predetermined equivalent ratio TFBYADF is set as the target equivalent ratio TFBYA0.
That is, in the processing of Step 12 to Step 14, the smaller one of the corrected target equivalent ratio TFBYA4 and the predetermined equivalent ratio TFBYADF is selected and set as the final target equivalent ratio TFBFA0. Note that the processing from step 12 to step 14 corresponds to the condition establishment prohibiting means, and in particular, the processing from step 14 corresponds to the limiting means.
[0040]
In step 15, it is determined whether to switch the combustion state from stratified combustion to homogeneous combustion. Specifically, it is determined whether or not the target equivalent ratio TFBYA0 is equal to or greater than the equivalent ratio threshold value TFACH. This routine ends. Note that the processing in step 15 corresponds to a switching condition determination means.
[0041]
In step 16, since all the conditions for switching to homogeneous combustion are satisfied, the combustion determination flag FSTRR is set to “0” (during homogeneous combustion) to switch to homogeneous combustion. Then, combustion control based on the combustion determination flag FSTRR is performed by another routine (not shown) (combustion state switching means).
According to such processing, the corrected target equivalent ratio TFBYA4 obtained by performing the phase lag correction on the basic target equivalent ratio TFBYA00 after the predetermined time CFD has elapsed from the start of deceleration is equal to or higher than the equivalent ratio threshold value TFACH. When it becomes, it is determined that the condition for switching the combustion state from stratified combustion to homogeneous combustion during deceleration is satisfied. Therefore, since the target equivalent ratio TFBYA0 is gradually switched, torque fluctuation during switching of the combustion state can be smoothed. Also, by delaying the timing for switching the map for calculating the target equivalent ratio TFBYA0, it is possible to absorb the response delay of devices such as the evaporated fuel processing device and the exhaust gas recirculation device, and the combustion immediately after switching becomes unstable. It is prevented. Furthermore, since the switching to the homogeneous combustion is prohibited until the fuel cut is performed at the time of deceleration, it is possible to prevent the exhaust property from being deteriorated.
[Brief description of the drawings]
FIG. 1 is a diagram corresponding to claims of claim 1 of the present invention. FIG. 2 is a system configuration diagram showing an embodiment of the present invention. FIG. 3 is a timing chart showing control contents. Flowchart showing [FIG. 5] Flowchart showing control contents same as above
DESCRIPTION OF SYMBOLS 10 Cylinder injection type internal combustion engine 13 Combustion chamber 18 Fuel injection valve 50 Control unit 51 Accelerator sensor 52 Crank angle sensor

Claims (6)

An internal combustion engine in which the combustion state can be switched between stratified combustion and homogeneous combustion by switching the combustible air-fuel mixture in the combustion chamber between stratified combustion and homogeneous combustion, and when the deceleration is performed during stratified combustion, the deceleration is reduced. The fuel supply is stopped after the elapse of a first predetermined time from the start, and the target equivalent ratio in the stratified combustion is changed from the target equivalent ratio in the stratified combustion until the first predetermined time elapses after starting the deceleration. In the internal combustion engine fuel supply control device for switching to
An operating state detecting means for detecting the engine operating state, a target equivalent ratio calculating means for calculating a target equivalent ratio according to the detected operating state, and gradually changing the target equivalent ratio with respect to the calculated target equivalent ratio Target equivalence ratio correcting means for correcting to delay, switching condition determining means for determining whether or not a switching condition from stratified combustion to homogeneous combustion is established based on the corrected target equivalent ratio, and switching to homogeneous combustion A fuel supply control device for an internal combustion engine, comprising: combustion state switching means for switching the combustion state from stratified combustion to homogeneous combustion when the condition is satisfied. The target equivalent ratio calculation means calculates a target equivalent ratio to be calculated when a second predetermined time shorter than the first predetermined time has elapsed since the start of deceleration, from a target equivalent ratio in stratified combustion to a homogeneous combustion. The fuel supply control device for an internal combustion engine according to claim 1, wherein the control is performed to switch to a target equivalent ratio.   The switching condition determining means includes condition establishment prohibiting means for prohibiting establishment of a switching condition from stratified combustion to homogeneous combustion until the first predetermined time has elapsed. Fuel supply control device for internal combustion engine.   The switching condition determining means determines that the switching condition from stratified combustion to homogeneous combustion has been established when the target equivalent ratio corrected by the target equivalent ratio correcting means is equal to or greater than a predetermined equivalent ratio threshold value. The fuel supply control device for an internal combustion engine according to any one of claims 1 to 3, which has a configuration.   The condition establishment prohibiting means includes a limiting means for limiting the target equivalent ratio corrected by the target equivalent ratio correcting means to be less than the equivalent ratio threshold value during the first predetermined time. 5. A fuel supply control device for an internal combustion engine as set forth in claim 4. An internal combustion engine in which the combustion state can be switched between stratified combustion and homogeneous combustion by switching the combustible air-fuel mixture in the combustion chamber between stratified combustion and homogeneous combustion, and when the deceleration is performed during stratified combustion, the deceleration is reduced. In the fuel supply control device for an internal combustion engine that stops the fuel supply after a lapse of a predetermined time from the start and shifts the target equivalent ratio to switch the combustion state from stratified combustion to homogeneous combustion,
A fuel supply control device for an internal combustion engine characterized by gradually changing a target equivalence ratio calculated according to an engine operating state when switching the combustion state from stratified combustion to homogeneous combustion.

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